function [ color_ramp ] = color_ramp_greyscale( field )
n = size(field, 1);
color_ramp = zeros(n, 3);

vmax = max( field(:,1) );
vmin = min( field(:,1) );

parfor i_v = 1 : n
    v = field(i_v, 1);
    for i_rgb = 1 : 3
        color_ramp(i_v, i_rgb) = (v - vmin) / (vmax - vmin);
    end % FOR
end % parfor

end % FUNCTION

